Aircraft manufacturer research reveals the reason why there are so few cases of virus infection on board

Image courtesy : SpiceJet

Publisher : Civil Aviation Resource Network / https://www.minhangshi.com/news_8788253.html / Translation, editing : Gan Yung Chyan, KUCINTA SETIA

The International Air Transport Association (IATA, hereinafter referred to as "International Air Transport Association") pointed out that the risk of transmission of SARS-CoV-2 in the cabin is low and updated the published case data. Since the beginning of 2020, a total of 44 cases (including confirmed, possible and potential cases) that may have been infected with the virus during the flight have been reported. During the same period, about 1.2 billion passengers traveled by air.

"The risk of passengers on board being infected with the new coronavirus is very low. Only 44 cases or flight-related infections have been found out of 1.2 billion passengers, which is equivalent to only 1 case per 27 million passengers. If this proportion exists, it is underestimated. Assuming that 90% of infectious incidents are not recorded, there is only one case per 2.7 million passengers. This figure is enough to be very reassuring. In addition, the vast majority of reported cases have occurred in The anti-epidemic measures for wearing masks in the cabin have not yet been universally implemented.” IATA medical consultant Dr. David Powell (Dr. David Powell) pointed out.

Jointly released by Airbus, Boeing and Embraer, independent computational fluid dynamics (CFD) studies conducted by the three companies on their respective aircraft have revealed the reason for the extremely low number of infections in the cabin. Although the methods are slightly different, each detailed simulation confirms that the aircraft's ventilation system can indeed control the movement of particles in the cabin, thereby limiting the spread of the virus. The results from the simulated data are similar:

·Aircraft ventilation system, high-efficiency particulate air (HEPA) filters, natural barriers of seat backs, air flow from the top of the cabin to the floor, and high-frequency air exchange rate can effectively reduce the risk of virus transmission in the cabin.

During the epidemic, the epidemic prevention measures requiring passengers and crew members to wear masks in the cabin added an extra layer of protection. Compared with most other indoor environments, aircraft cabins are safer.

Data collection

The results of IATA data collection and individual simulations by aircraft manufacturers are consistent with the low numbers mentioned in a peer-reviewed study recently published by Freedman and Wilder-Smith in the Journal of Travel Medicine. Although it is impossible to restore the real scene of the infectious incident that may be related to the flight, the IATA concluded based on careful study of the documents published by airlines and public health authorities, there is no sign that the spread of the virus in the cabin is widespread or high. . In addition, Freedman/Wilder-Smith research also pointed out that wearing a mask can further reduce the risk.

Multilayer protection measures

The International Air Transport Association recommended wearing masks in the cabin in June. After the International Civil Aviation Organization (ICAO) issued and implemented the "Departure Guidelines", most airlines have this requirement. Although the special design of the cabin ventilation system has reduced the risk of virus transmission on board the aircraft to a very low level, the "Sailing Guide" further superimposed multi-layer protection measures to greatly reduce the risk of virus transmission in the cabin.

“The ICAO comprehensive guidance on safe air travel during the epidemic crisis relies on multiple layers of protection, covering multiple processes at the airport and on board. Wearing a mask is the most intuitive protection. In addition, passenger queue management and contactless passenger handling Processes, reducing the movement of people in the cabin, and simplifying in-flight services are also a number of protective measures taken by the aviation industry to ensure public health safety in flight. It is essential that the cabin ventilation system is highly efficient through high-frequency ventilation and air exchange. Filtering the circulating air can prevent the spread of the virus." Dr. Powell emphasized.

The layout design features of the aircraft cabin further enhance protection and reduce the probability of infection on the aircraft:

·The face-to-face interaction between people is limited, the passengers face the front and rarely walk in the cabin during the flight

·The seat back becomes a physical barrier, blocking the flow of air from one row to another

·Segmented airflow design, the air flows vertically from the top of the cabin to the floor, minimizing front and rear airflow

·A lot of fresh air enters the engine room. The cabin air change frequency of most airplanes is as high as 20-30 times per hour. Compared with the average air change frequency of 2-3 times per hour in the office or 10-15 times per hour in schools, the air is fresher

·The cabin ventilation system is equipped with HEPA filters, which can filter and remove more than 99.9% of bacteria and viruses, ensuring that the air entering the cabin is free of microorganisms

Aircraft manufacturer's research

Through the linkage of various design elements, the conclusion that the cabin becomes a unique low-risk indoor environment is intuitive. The three major aircraft manufacturers used computational fluid dynamics (CFD) modeling studies in their aircraft cabins to further confirm the above conclusions on the data. The key points are as follows:

Airbus

Airbus uses computational fluid dynamics (CFD) to perform highly accurate simulations of the air in the A320 cabin to see how droplets from coughing move through the cabin air. In the simulation, parameters such as air speed, direction, and temperature at 50 million points in the cabin were collected and calculated, up to 1,000 times per second.

Airbus uses the same tools to model the non-cabin environment, maintaining a distance of six feet (1.8 meters) between people. The conclusion is that sitting side by side on an airplane is less likely to be exposed to the virus when it is six feet away from an environment such as an office, classroom, or grocery store.

Mr. Bruno Fargeon, head of Airbus Engineering and Airbus Custody Trust, said: "After using the most accurate scientific methods to perform many detailed simulations, the data we obtained show that the cabin environment is safer than indoor public places. On the plane. The way of air circulation, filtration and exchange creates an absolutely unique environment where there is as much protection for people sitting side by side as people standing six feet apart on the ground."

Boeing Company

Researchers at Boeing use computational fluid dynamics (CFD) to track how droplets in coughs and breaths move in the cabin. The study covers a variety of scenarios, including whether the coughing passenger wears a mask, the coughing passenger is in various seats including the middle seat, and the various changes in the opening and closing of the air outlet above the passenger's head.

Mr. Dan Freeman, chief engineer of Boeing's Confidence Travel Program, said: “The simulation study has learned the number of cough droplets entering the breathing space of other passengers and compared similar conditions in other environments (such as conference rooms). According to The amount of particulate matter in the air, and the environment of passengers sitting next to each other on the plane is equivalent to a standing scene more than seven feet (or two meters) in a typical indoor environment of a building.

Embraer

Embraer uses computational fluid dynamics (CFD) to verify cabin air flow and droplet diffusion models in a full-scale cabin environment test. When analyzing the cabin environment, it considers the cough conditions of passengers on different seats and different aircraft models. Air flow, measure and calculate the above variables and their effects. Embraer’s research shows that the risk of virus transmission in aircraft cabins is extremely low, or actual data on cabin-borne viruses that have occurred also support this finding.

Mr. Luis Carlos Affonso, Senior Vice President of Engineering, Technology and Strategy at Embraer, said: "People's travel needs, the desire to connect with the world and the need to visit relatives and friends have not disappeared. In fact. At times like this, we need family and friends even more. The message that needs to be delivered today is that thanks to the use of appropriate technology and procedures, you can fly safely—all studies have proven this. In fact, during the epidemic, The cabin of a commercial aircraft is safer than any indoor space."

Safety is the top priority of the aviation industry

The research work not only demonstrates the sincere cooperation and dedication of all parties in the air transport industry to ensure flight safety, but also provides evidence of cabin air safety.

The aviation industry has a reputation for ensuring the safety of every flight. During the epidemic, ensuring public health safety during flight is equally important. A recent IATA study found that 86% of recent travelers believe that the deployment and implementation of epidemic prevention and control measures in the aviation industry can ensure their safety.

Mr. Alexandre de Juniac, Chairman and Chief Executive Officer of the International Air Transport Association, emphasized: “There is no single measure that can ensure that we live and travel safely during the epidemic. But many measures have been taken. It can reassure travelers around the world that the new coronavirus has not yet destroyed their freedom of flight. There is no risk of zero in the world. There have been 44 cases or flight-related cases among 1.2 billion passengers, and there is a risk of infection on board. The probability of being struck by lightning is of the same order of magnitude, and both are extremely small."

The detailed computational fluid dynamics research conducted by the aircraft manufacturer shows that the existing design and function of the aircraft, combined with the measures of wearing face masks for passengers and crew members, can reduce the risk of virus transmission in the cabin. Airlines, aircraft manufacturers and every individual/institution related to the aviation industry will, as always, be guided by science and global best practices to ensure the safety of passengers and crew. "Mr. de Juniac added.